Osiris' bonuses are offensive and diverse. He improves several aspect of Camelry, turning them into all-round cavalry with an impressive speed of 7.2. He also improves Kebenits, probably giving a player the edge in naval battles. His God Power, Son of Osiris, transforms the Pharaoh into an incredibly powerful hero. He also allows for the creation of another Pharaoh. This allows the normal Pharaoh to stay at the base empowering buildings, while the Son of Osiris can wreak havoc on the battlefield. Alternatively, the player can have two Pharaohs empowering, a useful bonus for Isis players. (In older versions of the game, the Son of Osiris god power causes a glitch when New Kingdom is researched, allowing another Pharaoh to spawn, giving three Pharaohs – 1 Son of Osiris and 2 regular Pharaohs.)

In the Age of Mythology campaign, Osiris appears as an non-controllable God in a cut scene. Osiris also appears in the scenario editor as a special God-strength hero unit, far more powerful than any other unit. Unlike the greater Titans such as Prometheus and Kronos, Osiris has fewer hit points and cannot regenerate them. However, Osiris makes up for this by having the highest amount of armor in all categories as well as the highest attack of any unit in the game. In addition, Osiris can unleash mighty chain lightning attacks that deal splash damage to a group of enemy units at a distance. This makes Osiris the strongest unit in the entire game. He can easily defeat Titans such as Gaia even when outnumbered.

Being a hero unit, the stats and abilities of Osiris can be improved by technologies that benefit heroes. The type of these abilities and its scope of impact depends on what civilization is played in the scenario editor.

If played as the Greeks, researching Olympic Parentage increases Osiris' hit points by 5,000.

He is the father of Horus by Isis and Anubis by Nephthys. His brother is Set and sisters are Isis and Nephthys, His father and mother are Geb and Nut respectively. He was cut to pieces by his evil brother Set, but Isis bound them together by mummification, and resurrected him. He then moved to the underworld to be the god of the dead, but not before conceiving Horus.